Property

The terraces of Langen continue to grow: The German company Bonava has completed the first multi-family houses in passive standard with high energy efficiency. There is even an instruction manual for this.

The ventilation system is hidden in a small door in the corridor of the chic new apartment in Elisabeth-Selbert-Allee. Large white hoses and a filter system provide fresh air in the new building. The Langener Terraces, which Bonava (formerly NCC) has been constructing in Elisabeth-Selbert-Allee since 2013, will receive an interesting innovation in the fifth and final construction phase with building number six and number seven: they are the first Bonava apartment buildings to passive house standard.

The last 72 apartments, out of a total of 250 completed apartments, will be handed over to their new owners in the next few days. With the exception of the supply and exhaust air ventilation pipes at the level of the bathrooms, there is hardly any difference to the neighbouring blocks from the outside, but inside the houses there is real technology of the future. “The apartments already meet the high energy efficiency requirements set by legislators for 2021,” explains Bonava project manager Eckard Sommer.

Discipline needed

The two new buildings, which, like the other houses in the neighbourhood, are U-shaped and terraced, have special thermal insulation and an airtight building envelope. Thus practically no energy is lost. The ventilation system with built-in heat recovery ensures a pleasant climate in the rooms. Eckhard Sommer also knows the pitfalls of the passive house standard: “The system only works if all residents adhere to the rules,” the project manager knows. This means, for example, that no window may be tilted any longer, as otherwise energy escapes unnecessarily.

“In order to use the energy savings correctly, discipline is needed from the owners,” continues Eckhard Sommer. But the 60-page operating manual for the highly technical filter system certainly contains the important tips. The owners follow the rules, but amazing energy savings can be achieved: Only about 15 kilowatt hours of energy per square meter are consumed per year. For comparison: a house built ten years ago needs 100 kilowatt hours, a house built in the 1970s needs 200 to 300 kilowatt hours per square meter per year.

However, the investment in the future is not quite cheap: the apartment costs around 200 to 300 euros more per square metre. The 72 apartments with three- to five-room layouts “are between 60 and 150 square metres in size and the new owners had to invest 3,700 to 4,000 euros in them. Bonava has made an investment of 30 million euros for this project.

Sold or reserved

Langen, however, continues to grow in the Elisabeth-Selbert-Allee. Opposite the Langener Terrassen, construction work is already underway on another residential park with 36 semi-detached and terraced houses. A good third of these houses have already been sold or reserved. Another apartment building with 55 apartments is expected to go on sale in autumn. Work is also progressing elsewhere. Bonava wants to create a new home for 950 families on the 18.5 hectare site between Liebigstraße and Hans-Kreiling-Allee. Construction of the houses can also begin in 2019.

Langen’s mayor Frieder Gebhardt is glad that the city has such a reliable partner in Bonava. “For our growth course, we need players who are prepared to invest in the Langen location,” emphasizes the city hall manager. With such special projects as the multiple dwelling in passive standard the enterprise is besides a model for other developers in the area of the energy conservation and in environmental protection.